Collagen-containing connective tissues play a fundamental role in maintaining the correct structure and function of the eye. The importance of collagen in the eye is demonstrated by its natural abundance, with approximately 80% of the eye comprising collagen. The properties of collagen, namely its strength and elasticity, help maintain the curved geometry of the eye ball, which is necessary for the eye to function properly.
In addition, collagen also helps the eye ball cope with changes in internal pressure by maintaining the necessary rigidity and elasticity that prevent the eye from bursting/rupturing and/or collapsing.
The weakening and/or degradation of structural proteins (such as collagen) in the eye is symptomatic of a number of eye disorders (referred to herein as collagenic eye disorders). Illustrative examples of collagenic eye disorders include various forms of corneal ectasia (non-inflammatory corneal ectasia, e.g. keratoconus, keratoglobus, pellucid marginal degeneration; inflammatory corneal ectasia; iatrogenic corneal ectasia (keratectasia), e.g. following laser refractive procedures/refractive surgery (LASIK, LASEK, PRK); or myopia). In addition, collagenic eye disorders include disorders in which the collagen in the eye, particularly the cornea or sclera, is weakened and/or degraded as a consequence of inflammation, infection, injury or corneal oedema.
By way of example, keratoconus is a degenerative disorder that results in a weakening of the collagen in the eye, which ultimately leads to progressive distortions in the shape of the eye ball. This progressive change in the eye's shape causes the eye to adopt a more conical shape over time which, in severe cases, can result in visual deterioration and eventual blindness.
Current methodologies for the treatment of keratoconus, and other related disorders, seek to strengthen the weakened collagen by photochemically cross-linking the collagen with riboflavin (vitamin B2). This technique, commonly known as corneal cross-linking or CXL. The procedure involves the application of riboflavin to the eye followed by exposure to UV radiation to initiate the photochemical cross-linking of the collagen with the riboflavin. However, the exposure of the eye to UV radiation can result in damage to the corneal endothelium and/or epithelium. In the most severe cases, retinal degeneration can occur. The CXL procedure also requires the top layer of the epithelium of the eye to be removed in order to enhance riboflavin penetration into the corneal stroma. The removal of the top layer of the epithelium from the eye requires delicate surgical techniques and also carries a risk of infection. As a consequence, specially trained medical practitioners and equipment are required in order to treat keratoconus and related disorders.
There is, therefore, a need for improved approaches for treating collagenic eye disorders in which cross-linking of collagen in the cornea and/or the sclera of the eye is beneficial.
The present invention was devised with the foregoing in mind.